Talk:Dorsal root ganglion

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I think it also has the cell bodies for the visceral sensory (sympathetic)

It is true that the dorsal root contains visceral sensory axons, and that the DRG contains their cell bodies. However, I think the name sympathetic does not fit, bc the autonomic side is usually reserved for visceral efferent (not sensory). In any event the first google book search result confirms that visceral sensory neurons are in the dorsal root. Lecture Notes on Human Physiology

By John J. Bray, Anthony D. C. Macknight 

Mbarden 23:23, 5 October 2007 (UTC)

I've rolled back this edit from an anon making their first edit. Anyone here have any opinions about the validity of the edit? --Arcadian 20:47, 12 August 2006 (UTC)

I think 'neurology' should be replaced with 'neuroscience'. Neurology is the study of brain and nervous system disorders. This article is about intact, functioning DRG and relates to its role and functioning in the central and peripheral nervous system - neuroscience. [robert B. 11/11/11] — Preceding unsigned comment added by 130.88.99.217 (talk) 12:09, 11 November 2011 (UTC)

Chicken ganglion picture

The picture of the chick ganglion is cool, but it doesn't contribute to the explanation of a ganglion. Does anyone agree on removing it? 207.42.135.25 (talk) 00:23, 25 May 2009 (UTC)

We can add a section to the article about growth factors that support sensory neuron survival axon growth and other aspects of DRG function. Recent review: Role of neurotrophin signalling in the differentiation of neurons from dorsal root ganglia and sympathetic ganglia. --JWSchmidt (talk) 18:14, 5 June 2009 (UTC)

Mechanosensitive channels

The dorsal root ganglion is an important structure in terms of sensory neurons, so I thought that a section detailing the presence of mechanosensitive channels in the dorsal root ganglion would add to the overall bigger picture of the structure. These channels are an important of the function of the dorsal root ganglion. Ktrychta (talk) 04:22, 2 December 2011 (UTC)

Location

The dorsal root ganglia lie along the vertebral column by the spine: not very helpful, especially as in this context, vertebral column and spine mean the same thing, pretty much. At what bony level is, say, the L_{4 - 5} dorsal root ganglion? I believe it is close to the level of the L_{4 - 5} intervertebral foramen, meaning that the L_{4 - 5} components of the cauda equina are not spinal nerves but separate motor and sensory nerve roots. According to The Anatomy Guy (personal communication), this is the correct picture, but I have yet to see it discussed in a text book. Moletrouser (talk) 10:08, 5 May 2013 (UTC)

Dendrites

I find mention of dendrites confusing here. After all, we are told elsewhere that pseudounipolar neurons do not have dendrites - which makes sense, because if they had them, what use would they be? The cell body is far away from both the distal and the proximal ends of the axon, so what would be signalling to its dendrites if they existed? Moletrouser (talk) 10:25, 5 May 2013 (UTC)

@Looie496: Moletrouser, I think you're right, and that therefore the whole section about 'dendrites' should be removed, but I've not learned enough about neurons to confidently do so, so I've tried to 'ping' Looie496 in the hopes that he can address this issue. I do think that you're quite right that there are NOT any 'dendrites' involved, that in fact both branches are AXONS, with a TRIGGER ZONE at the section of the distal (sensory) end immediately adjacent to a sensory bulb or other input structure, which upon sensory input can result in an action potential along that myelinated axon, on past the actual soma, and continuing on down the proximal axon. But this 'dendrite' misunderstanding regarding pseudounipolar neurons seems to be widely prevalent, because we're taught that inputs are defined as dendrites, and the error exists in textbooks and online coursework and pictures as well. Perhaps we need to better understand the deeper defining characteristics between dendrites and axons; here's two sources which seem to be trustworthy:

"Dendrites have tapered shape, are relatively short, and contain large amounts of endoplasmic reticulum. Axons are narrow, do not taper, and have little endoplasmic reticulum." Ch 14, pp 563 Miller's Anatomy of the Dog, 4th ed, By Howard E. Evans, Alexander de Lahunta;

and, while I find it difficult to follow & understand, and it's not directly related specifically to the fundamental differences between axons & dendrites, it does mention important differences which may be relevant: "dendrites contain some synthetic machinery including ribosomes and Golgi outposts, while axons contain little, if any, of these components (Bartlett and Banker, 1984; Craig and Banker, 1994) (Fig. 1). Similarly, the rough endoplasmic reticulum may extend a little way into the dendrites, but is absent from the axon, although the smooth endoplasmic reticulum is found throughout the neuron (Krijnse-Locker et al., 1995). The cytoskeletal framework of axons and dendrites also differs. Axons contain high levels of neurofilament proteins and dendrites do not, and MAP2 is a dendrite-specific microtubule-binding protein, while dephosphorylated tau, which also associates with microtubules, is found at high levels only in axons (Peng et al., 1986; Craig and Banker, 1994)". (above from http://jeb.biologists.org/content/218/4/572#sec-2 , third paragraph of third section, 'Overview of neuronal polarity')

So the upshot seems to be that while there are lots of places which confusingly identify the sensory ends of pseudounipolar neurons as 'dendrites' just because they function as inputs, there seem to be important micro-anatomical and physiological differences that instead correctly (though hard to find!) identify the sensory ends as AXONS. UnderEducatedGeezer (talk) 11:37, 30 March 2016 (UTC)

@Looie496: (or anyone else who has good knowledge about psuedo-unipolar neurons not having dendrites) I wonder if it would be reasonable now to delete the information about dendrites?. UnderEducatedGeezer (talk) 02:47, 4 January 2018 (UTC)

Ok, this issue has existed for 3 years, so I'm going to be bold and remove the section which refers to parts of the pseudounipolar neurons as dendrites. The rest of that portion of the article reads fine without it. Anyone who knows better can revert as they wish. UnderEducatedGeezer (talk) 07:29, 26 April 2019 (UTC)

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DRG: inside or outside the dura of the spinal cord?

Is the dorsal root ganglia inside or outside the dura of the spinal cord, that is, is it part of the central nervous system, or the peripheral nervous system? (And exactly how does the CNS transition to the PNS?)UnderEducatedGeezer (talk) 23:14, 8 May 2020 (UTC)

• They are part of the PNS. PNS nerves synapse with the CNS within the grey matter of the spinal cord. The synapse itself is where the PNS and CNS are distinguished (PNS is after or 'post synaptic', CNS is 'pre synaptic') --Tom (LT) (talk) 07:58, 4 October 2020 (UTC)